i have an '03 with "about 200,000" miles on it and starting last winter my heater core went out and in the past 3 months i have replaced the heater core 3 more times. ive gone thru every checklist and troubleshooting list i can think of and still the heater core goes out? flushed cooling system, replaced radiator cap, replaced thermostat, and checked the coolant for an electrical charge and never shows more than .03 amps. any suggestions or comments would be greatly appriciated, i have got pulling the heater core out down to a science and have it out of the truck in under an hour

 

how is the core failing ?

 

Make sure there are no shirts in the wiring. And when you start the truck do you still have it plugged in?

 

it keeps failing in different places on the heater core, sometimes its on the end of one of teh cores and sometimes it leaks around either the inlet or exit pipe? and thats the next thing i need to check, i have some stereo stuff in the truck, would that be a good place to start checking the wiring and grounding?

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i spent a good couple hours tracing wires and checking connections and cleanliness on battery terminals and looking for frayed or exposed wires and have not found any problem areas? one thing is from the heater core leaking there is still alot of moisture around the carpet in the front seats, could that be a part of the problem? also I've been told of people putting a zinc diode somewhere on the cooling system to collect any electrical current that may be present? is that a myth or would that be a good solution?

 

Maybe somebodys sellin you junk

 

Blown headgasket ? building pressure in the Heater Core ?

 

i would hope the dealership wouldnt sell me crap parts!! jw if the headgasket was blown wouldnt i see fluid leaking out of the side of teh head? havent spotted any leaks anywhere?

 

Not always it could be a internal leak alongside a water jacket

 

and what would be the best way to go about checking for a leak thats internal?

 

I work on freightliners, and they have this same issue. We put restrictors on the outlet side of the heater core. We cut the rubber line outside the fire wall(outlet) and install a restrictive fitting. you can pick up the fitting at freightliner if you cant find one.

if your head gasket was blown you would have lots of psi in your cooling system, a cracked head will also somtimes cause lots of psi in cooling system. you can check it by installing a coolant pressure tester on the radiator and running the truck, 1500 rpm for about 10 mins, shouldnt build more than like 15-20 psi. (note this is how we test for a bad head or head gasket on big rigs, not sure if its accurate for your truck) I think the restrictive fitting will solve your issue.